1. Field of the Invention
The invention relates to a process for producing ethanol.
2. Description of Related Art
The process for producing ethanol from fermentation of whole grain mashes is well known.
The addition of alkaline protease enzymes to mash has been shown in Biomass 16 (1988) 77-87 to increase amino nitrogen sufficient to support accelerated rates of ethanol fermentation: the addition of a protease, an alkaline protease derived from Streptomyces griseus, to sorghum or milo mash resulted in higher ethanol fermentation rates.
Canadian Patent 1 143 677 describes a process for producing ethanol form amylaceous raw stock, such as wheat, barley or rye. This process comprises a step of hydrolyzing starch, cellulose and some other substances contained in corn grains in the presence of a complex hydrolytic enzyme produced by a fungi Trichoderma koningii, and containing C.sub.1 -enzyme, endo- and exoglucanase, cellobiase, xylanase, beat-glucosidase, protease, and a number of amylolytic enzymes.
However these processes do not allow the production of ethanol when a higher dry solids mash level is present in the fermenter.